Costalin Mehdi, Rousselot Steeve, Lepage David, Foran Gabrielle, Prébé Arnaud, Aymé-Perrot David, Dollé Mickael
Department of Chemistry, Université de Montreal, 1375 Avenue Thérèse-Lavoie-Roux, Montreal H2V 0B3, Quebec, Canada.
Prospective Lab, Total SA, Paris La Défense 92069, France.
ACS Appl Mater Interfaces. 2023 Sep 6;15(35):42015-42025. doi: 10.1021/acsami.3c06152. Epub 2023 Aug 23.
Lithium metal has generated significant interest as an anode material because of its high theoretical capacity. However, issues such as dendrite growth and lithium loss during cycling make this material incompatible with liquid electrolytes. Solid polymer electrolytes (SPE) have been proposed as replacements as they are non-flammable, resist dendrite growth, have decent ionic conductivity, and have low resistance with lithium metal. Passivation layers, which form on the lithium metal surface and are hence intrinsic to its chemical composition, are often overlooked. Residual quantities of atmospheric gases are present in lithium metal storage environments, making surface modification and its subsequent impact on anode reactivity inevitable. Moreover, the impact of this phenomenon in a realistic lithium metal anode (LMA) environment with SPE has not yet been extensively investigated. In this study, the impact of gas exposure on an LMA was investigated by exposing freshly cut lithium rods to O, CO, and N. Passivation layers were characterized via X-ray photoelectron spectroscopy. The effect of passivation layer formation on LMA reactivity toward SPE was measured by exposing passivated samples to common SPE materials. The resultant interface was characterized using Raman spectroscopy. SPE-passivation layer reactivity was correlated to ageing by electrochemical impedance spectroscopy and kinetic charge transfer via galvanostatic linear polarization at the LMA-SPE interface in symmetric Li─SPE─Li stacks. This study revealed that the chemical composition of the passivation layer affects LMA reactivity toward SPE and electrochemical performance. A thorough characterization of the lithium metal passivation layer is essential to understanding the fundamental factors affecting solid-state lithium metal battery performance.
锂金属因其高理论容量而作为阳极材料引起了广泛关注。然而，诸如枝晶生长和循环过程中的锂损失等问题使得这种材料与液体电解质不相容。固体聚合物电解质（SPE）已被提议作为替代品，因为它们不可燃、能抑制枝晶生长、具有良好的离子导电性，并且与锂金属的电阻较低。钝化层形成于锂金属表面，因此是其化学成分所固有的，却常常被忽视。锂金属储存环境中存在残留的大气气体，使得表面改性及其对阳极反应性的后续影响不可避免。此外，这种现象在具有SPE的实际锂金属阳极（LMA）环境中的影响尚未得到广泛研究。在本研究中，通过将新切割的锂棒暴露于O、CO和N中来研究气体暴露对LMA的影响。通过X射线光电子能谱对钝化层进行了表征。通过将钝化样品暴露于常见的SPE材料来测量钝化层形成对LMA与SPE反应性的影响。使用拉曼光谱对所得界面进行了表征。通过电化学阻抗谱将SPE - 钝化层反应性与老化相关联，并通过对称Li─SPE─Li电池组中LMA - SPE界面处的恒电流线性极化来研究动力学电荷转移。本研究表明，钝化层的化学成分会影响LMA与SPE的反应性以及电化学性能。对锂金属钝化层进行全面表征对于理解影响固态锂金属电池性能的基本因素至关重要。
